[PATCH v2 2/3] nvmem: stm32: add warning when upper OTPs are updated

From: Patrick Delaunay
Date: Mon Oct 17 2022 - 11:51:02 EST


As the upper OTPs are ECC protected, they support only one 32 bits word
programming.
For a second modification of this word, these ECC become invalid and
this OTP will be no more accessible, the shadowed value is invalid.

This patch adds a warning to indicate an upper OTP update, because this
operation is dangerous as OTP is not locked by the driver after the first
update to avoid a second update.

Signed-off-by: Patrick Delaunay <patrick.delaunay@xxxxxxxxxxx>
---

(no changes since v1)

drivers/nvmem/stm32-romem.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/nvmem/stm32-romem.c b/drivers/nvmem/stm32-romem.c
index d93baee01d7b..bb8aa72ba2f9 100644
--- a/drivers/nvmem/stm32-romem.c
+++ b/drivers/nvmem/stm32-romem.c
@@ -132,6 +132,9 @@ static int stm32_bsec_write(void *context, unsigned int offset, void *buf,
}
}

+ if (offset + bytes >= priv->lower * 4)
+ dev_warn(dev, "Update of upper OTPs with ECC protection (word programming, only once)\n");
+
return 0;
}

--
2.25.1